In cabinets, cases, and other similar structures, brackets or other shelf supports are used for attaching the shelf to the walls inside the structure. Many of brackets include a planar body member formed of injection molded material having a post which is inserted into a receiving hole inside the cabinet for retaining the bracket thereto. The shelf usually rests on a ledge extending horizontally from the planar body member.
Some support brackets include a locking mechanism for retaining the shelf to the bracket when the bracket is in place. For example, U.S. Pat. No. 4,666,117 discloses a shelf lock having a planar body member formed of two integral halves joined together at an angle and forming a rectangular opening. A crescent shaped planar protrusion is positioned over the opening and has a lower shelf engaging edge for retaining the shelf in position on the ledge. The shelf is locked into position by sliding the shelf over the protrusion, depressing the protrusion and allowing the shelf edge to move onto the ledge. Afterward, the protrusion springs back to where the lower shelf engaging edge is locked over the shelf.
When the shelf engaging edge is biased rearwardly, it tends to pivot away from the top of the shelf about an undefined point above the ledge. The angled upper half of the body counters this problem and provides a second pivoting movement of the upper half to counteract the pivotal movement of the shelf engaging edge. However, the thickness of the shelf must be to within a strict tolerance for the movement pivoting motion to work.
U.S. Pat. No. 4,830,323 discloses a shelf support in which a shelf engaging edge moves perpendicular to the body portion when returning to its original position once the shelf edge has been inserted. Thus, the shelf and support may have greater clearance. The structure includes two flexible limbs extending upwardly from the body portion. A V-shaped upper portion is positioned on the limbs.
The lower edge of the V-shaped upper portion defines a shelf engaging edge which engages the top portion of the shelf when it is slid into position onto a ledge extending forwardly from the body portion. As the shelf moves over the V-shaped upper portion, the limbs twist and are forced apart to accommodate flattening of the V-shaped portion. When the shelf is positioned over the ledge, the limbs twist back into their prone position in which the shelf engaging edge is positioned over the shelf to retain the shelf in position. Although this structure allows clearance between the shelf engaging edge and the ledge, the structure is not as rigid as desired because the limbs must be designed flexible enough to allow them to twist and be forced apart. When the structure is injection molded as a one-piece unit, the structure is inherently weaker because the unit must be designed flexible enough to allow the arms to twist apart as the shelf moves over the protrusion.